On the eve of Israeli Prime Minister Benjamin Netanyahu’s speech to Congress Tuesday, experts say the speech and the uproar that has blossomed around it are a sign of how Washington’s hyper-partisanship has moved into foreign policy.

Washington — Are deliberations in Congress on American foreign policy becoming more partisan?

That question arises on the eve of Israeli Prime Minister Benjamin Netanyahu’s speech to Congress Tuesday.

The Israeli leader – invited by House Speaker John Boehner outside of the traditional channels – is expected to blast President Obama’s diplomatic overtures to Iran, as well as the deal the administration and other international powers are negotiating with Iran on its nuclear program.

Democrats and Republicans, national security and foreign policy experts may be divided over the merits of Mr. Netanyahu’s arguments. But consensus is much stronger over the idea that the prime minister’s speech and the uproar that has blossomed around it are a sign of how Washington’s hyper-partisanship has moved into the foreign policy domain.

“At least since World War II there has been an effort by Congress, the White House, and the political parties to seek a bipartisan foreign policy, even if it doesn’t always work out that way,” says Mel Levine, a former Democratic congressman from California. “But what we’re seeing here is another deeply unfortunate by-product of the hyper-partisan atmosphere in Washington.”

In a speech Monday to the Washington conference of the American Israel Public Affairs Committee, Mr. Netanyahu sought to play down his discord with Mr. Obama over Iran and the controversy over his speech to Congress, saying the US-Israel “friendship will weather the current disagreement.” And Obama Monday said that, while there was “substantial disagreement” between the two countries, the debate over Iran would not be “permanently destructive” to US–Israeli relations.

The flap over Netanyahu’s speech is not the only case in recent memory of a foreign-policy debate displaying a hyper-partisan gulf.

Congressional hearings looking into the September 2012 terrorist attacks on US diplomatic facilities in Benghazi, Libya – and the Obama administration’s response to those attacks – revealed Republican suspicions of an administration cover-up and Democratic claims of a political witch hunt.

But the Netanyahu speech represents the first time a foreign leader is being enlisted in a way that drives the partisan foreign-policy wedge deeper, some Democrats say.

Mr. Levine, who served in Congress from 1983 to 1993, recalls that he and most of his fellow Democrats “really very forcefully disagreed with President Reagan on the Contra war he was conducting in Nicaragua. But the idea,” he adds, “that we would invite the principal international opponent of that war, Costa Rican President Oscar Arias, to speak to a joint session of Congress to explain why he disagreed with President Reagan – it was inconceivable.”

Asking "Is anyone thinking about the future?" Robert Kagan, a foreign policy analyst at the Brookings Institution, wondered in a Washington Post column Saturday what it might mean for foreign-policy debate if the "opposition party" while in control of Congress got in the habit of calling in "a foreign leader to speak to a joint meeting of Congress against a president and his policies."

Speculating what impact it might have had if Democrats in 2003 had summoned then-French President Jacques Chirac to speak on his opposition to President George W. Bush's impending war in Iraq, Mr. Kagan says the Netanyahu speech could presage "another weapon in our bitter partisan struggle."

At the time, like Netanyahu, Mr. Chirac insisted his position was in the best interest not just of his country but the world, the US included.

Republicans maintain there is nothing unusual about Netanyahu’s speech, saying it is part of an established tradition of foreign leaders speaking to Congress.

“The tradition of foreign leaders addressing Congress on issues of mutual concern goes back more than half a century,” Rep. Ed Royce (R) of California, chairman of the House Foreign Affairs Committee, said in a statement Sunday.

Representative Royce said Speaker Boehner “made the right decision” in inviting Netanyahu and encouraged members to attend the speech – a veiled reference to the three dozen or so Democrats who plan to sit out the address in protest of its partisan genesis.

Boehner arranged Netanyahu’s speech by going through Israel’s embassy in Washington and the Israeli ambassador, Ron Dermer, instead of following the usual path through the State Department.

It is because of the manner in which Netanyahu was invited – leaving the White House and the State Department out of the loop – that Democrats like Levine are calling the speech “unprecedented” and a partisan initiative.

But Royce also hinted at the partisan storm engulfing the speech, saying he could not “recall there ever being the level of contention that we are unfortunately seeing” surrounding the Netanyahu address, “no matter the views of the dozens of leaders who have addressed Congress.”

As if to underscore the sense of Netanyahu’s speech fitting into a tradition of foreign leaders addressing Congress, Boehner’s office announced Monday that with tomorrow’s speech, Netanyahu will become the only foreign leader to tie former British Prime Minister Winston Churchill’s record of speaking to Congress three times. The speaker plans to present the Israeli leader with a bust of Churchill.

Some members of Congress, apparently alarmed at the deepening partisan tone of the Iran debate, acted Monday to calm tensions – and to suggest that Congress still intends to address the Iran nuclear issue in a bipartisan manner.

House Foreign Affairs Committee Chairman Royce and the committee’s highest-ranking Democrat, Eliot Engel of New York, announced they would soon send a “bipartisan letter” to Obama citing “grave and urgent issues” in the negotiations on Iran’s nuclear program.

But at the same time, the statement said the letter’s signers expect to work with Obama to secure a strong deal that prevents an Iranian nuclear weapon through diplomacy.

“We remain hopeful that a diplomatic solution preventing Iran from obtaining a nuclear weapon may yet be reached,” the letter says, “and we want to work with you to ensure such a result.”